1. Field of the Invention
The present invention relates to a circuit arrangement for the energy-saving operation of a fluorescent tube. The invention comprises two connections each at both end caps, is electrically of mechanically accommodated in brackets via the connections, and is connectable with an alternating current supply by interconnecting a reactance coil and a starter.
Such a fluorescent tube generally consists of a tubular discharge vessel made of glass, into the end caps of which thermionic cathodes are melted. The discharge vessel is generally evacuated and filled with argon and mercury. At both end caps, the thermionic cathodes are routed to the outside as two connections each. Such a fluorescent tube is then electrically and mechanically accommodated in brackets via these connections. The operation of such a fluorescent tube is mostly effected at an alternating current supply, with a reactance coil and a glow discharge igniter, simply referred to as starter, being required for striking the gas discharge. However, the reactance coil and the starter imply an additional energy consumption or a reduction of the efficiency, respectively. Due to the fact that such a fluorescent tube is a comparatively economical and reliable light source, an efficiency in the order of only 0.5 is accepted.
2. Description of Related Art
It is known to use an electronic ballastxe2x80x94(elektronisches Vorschaltgerat) briefly referred to as EVGxe2x80x94for the energy-saving operation of a fluorescent tube. For this purpose, the EVG is connected between the alternating current supply and the connections of the fluorescent tube, with the reactance coil and the starter being replaced. From a circuit engineering point of view, the EVG thus represents a six-terminal network. By means of the EVG an efficiency in the order of nearly 1 can be achieved.
A great disadvantage is that electrical appliances, such as e.g. lamps, in which conventionally operated fluorescent tubes are employed can only be retrofitted to an energy-saving operation with EVG under extremely high efforts and expenditures. This is because a retrofit would mean time and labour-intensive installation costs apart from the procurement cost of the EGV, because in addition to the reactance coil and the starter the entire cabling would have to be replaced.
The invention is therefore based on the object to develop a circuit arrangement which renders itself for retrofitting the initially mentioned fluorescent tube in a simple manner for the energy-saving operation.
The solution of this object is effected by a circuit arrangement for the energy-saving operation of a fluorescent tube, which comprises two connections each at both end caps, is electrically and mechanically accommodated in brackets via the connections, and is connectable with an alternating current supply by interconnecting a reactance coil and a starter, characterised in that the circuit arrangement is a quadripole which transforms the current fed to its input terminals from the alternating current supply into a high frequency current which is output and its output terminal, whose input terminals form a series connection with the two connections at the one end cap and the reactance coil, the series connection being connected in parallel to the alternating current supply, and whose output terminals are electrically connected with the two connections at the other end cap. According to the same, the inventive circuit arrangement constitutes a quadripole which can be connected with the existing cabling in a simple manner after the opening of two lines. When connecting the inventive circuit arrangement all that has to be done is to make sure that the input terminals of the quadripole form a series connection with the two connections at the one end cap and with the reactance coil, the series connection being connected in parallel to the alternating current supply, and that the output terminals of the quadripole are connected electrically with the two connections at the other end cap. In other respects, interchanging of individual connections or terminals, respectively, proves to be uncritical because of the alternating current operation. Likewise, the series connection comprising the input terminals of the quadripole, the two connections at the one end cap, and the reactance coil which is connected in parallel to the alternating current supply can have any order. Insofar, the connection of the inventive circuit arrangement can principally be performed by anybody. Furthermore, the already existing coil will be retained upon a connection, because it assumes the function of a pre-filter for the inventive circuit arrangement, so that the construction of the inventive circuit arrangement requires only a small installation space and can be implemented economically.
Depending on which site the line into which the starter is connected is opened upon connection the starter is located either to the input or the output side of the inventive circuitry. In order to ensure a current flow for the proper function of the circuit arrangement the starter is bridged. For this purpose it is simply replaced with a short-circuited design in its existing bracket. In the case in which the starter is located on the input side of the inventive circuit arrangement it can advantageously be replaced with an electric fuse which can be inserted into the existing bracket and additionally protects the inventive circuit arrangement against overload.
The inventive circuit arrangement can be retrofitted in a particularly advantageous manner if it is integrated in the fluorescent tube or in one of the end caps of the fluorescent tube, respectively. In this case, only the fluorescent tube has to be replaced so that any intervention into the existing cabling is omitted. A further alternative can be that the inventive circuit arrangement is integrated in one of the brackets accommodating the fluorescent tube. With this alternative, retrofitting merely requires the replacement of the bracket(s).
The invention also relates to an device for the connection of an inventive circuit arrangement with an initially mentioned fluorescent tube. This inventive device is defined by the features of the characterising clause of claim 12.
By means of the inventive circuit arrangement it is already possible to retrofit an initially mentioned fluorescent tube for the energy-saving operation in a simple manner. Now, the inventive device for the connection of an inventive circuit arrangement enables retrofitting in a particularly advantageous manner, which neither requires an intervention in the existing cabling of the fluorescent tube nor a replacement of the fluorescent tube or its accommodating bracket(s).
For this purpose, the inventive device, on the one hand, comprises two contact receptacles which electrically accommodate the two connections of one of the end caps. On the other hand, the inventive device comprises two connections which are electrically accommodated in one of the brackets. The connections and the contact receptacles of the inventive device are electrically insulated against each other, with the connections of the inventive device being electrically connected with the input terminals, and the contact receptacles of the inventive device being connected with the output terminals of the inventive circuit arrangement. Due to the fact that the contact receptacles and the connections are arranged coaxially to one another the inventive device is of such a narrow installation size that it fits between an end cap of the fluorescent tube and the associated bracket.
The great advantage therefore is that retrofitting of the inventive circuit arrangement by means of the inventive device can be carried out in a manner as simple as the replacement of the fluorescent tube. For this purpose, the existing fluorescent tube is removed from its brackets, then the inventive device is plugged onto the connections at one end cap, and subsequently the fluorescent tube together with the inventive device is re-inserted between the brackets.
The inventive circuit arrangement itself can be arranged remotely from the inventive device, depending on the installation conditions of the electrical appliance in which the fluorescent tube is arranged, while the electrical connection between the inventive device and the inventive circuit arrangement can be made in a flexible manner via an electric cable. Due to the fact that the inventive circuit arrangement is a quadripole, a four-wire cable is preferably used. Both the inventive device and the inventive circuit arrangement can be arranged in respective housings which are optionally provided with electrical connecting contacts for a simple connection by means of the cable.
In a particularly preferred manner, however, the inventive circuit arrangement is arranged in the housing of the inventive device or in a common housing, respectively. In the ideal case, the housing of the inventive device comprises an extension extending parallel to the longitudinal axis of the fluorescent tube, which accommodates the inventive circuit arrangement. In this manner, the inventive circuit arrangement and device can be retrofitted in a particularly simple way and without interfering with the constructional conditions.
As an essential for the invention the cost advantage should be mentioned which results from the fact that both standardised fluorescent tubes can remain in service and the standardised distance between the brackets accommodating the fluorescent tube can be retained.
Due to the advantages which can be achieved with the invention with respect to energy saving and simple retrofittability, the inventive circuit arrangement and device are suitable in a special manner for the use in electrical appliances in which one or several fluorescent tubes are operated, such as e.g. lamps, solar booth lamps or the like.
The invention and further advantageous features thereof will be explained in more detail in the following with reference to the drawing in which: